import java.io.IOException;

public class Main{

	/**
	 * @param args
	 * @throws IOException
	 * @throws NumberFormatException
	 */
	public static void main(String[] args) throws NumberFormatException,
			IOException {
		java.io.BufferedReader r = new java.io.BufferedReader(
				new java.io.InputStreamReader(System.in));

		int number = -1;
		while (true) {
			number = Integer.parseInt(r.readLine());
			if (number == 0) {
				break;
			}
			String a = r.readLine().trim();
			String res = "";

			for (int i = 0; i < number; i++) {
				res += a.charAt(i);
				for (int j = 2;; j += 2) {
					if (j * number - i - 1 < a.length()) {
						res += a.charAt(j * number - i - 1);
					} else {
						break;
					}
					if (j * number + i < a.length()) {
						res += a.charAt(j * number + i);
					} else {
						break;
					}
				}
			}
			System.out.println(res);
		}
	}
}
